合成路线1

Hydrogenation of 6-nitrocoumarin (I) in the presence of Pd/C and di-tert-butyl dicarbonate provided (II). Partial reduction of the lactone function of (II) with DIBAL at low temperature gave rise to lactol (III), which was submitted to a Wittig condensation with (ethoxycarbonyl)triphenylphosphorane (IV) yielding chromaneacetic acid ethyl ester (V). The Boc protecting group of (V) was then removed with trifluoroacetic acid to afford aniline (VI), which was acylated with 4-cyanobenzoic acid (VII) in the presence of EDC to give amide (VIII). Addition of H2S to the nitrile group of (VIII), followed by S-methylation provided (IX). Then, displacement of the methylthio group of (IX) by ammonium acetate and further treatment with di-tert-butyl dicarbonate yielded the Boc-protected benzamidine (X). Finally, Boc-deprotection with trifluoroacetic acid furnished the title amidino ester.